macro(macro_ensure_out_of_source_build)
	if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
		message(FATAL_ERROR "In-source builds are not allowed.
Please create a directory and run cmake from there, passing the path
to this source directory as the last argument.
This process created the file `CMakeCache.txt' and the directory `CMakeFiles'.
Please delete them.")
	endif()
endmacro(macro_ensure_out_of_source_build)

